Separation of azeotropic mixtures using air microbubbles generated by fluidic oscillation

The feasibility of separating the azeotropic mixture of ethanol‐water using microbubble‐mediated batch distillation is presented. The effects of the depth of the liquid mixture in the bubble tank and of the inlet air microbubble temperature on the process efficiency were investigated. The enrichment of ethanol in the vapor phase was higher than that achieved at equilibrium conditions for all liquid ethanol mole fractions considered, including the azeotrope. On decreasing the depth of the liquid mixture and increasing the temperature of the air microbubbles, the separation efficiency of ethanol was improved. Ethanol with purity of about 98.2 vol % was obtained using the lowest liquid level (3 mm) in conjunction with the highest air microbubble temperature (90°C). Separation was achieved with a small rise in the temperature of the liquid mixture (4°C) at a depth of 3 mm and evaporation time of 90 min making this system suitable for treating thermally sensitive mixtures. © 2015 American Institute of Chemical Engineers AIChE J, 62: 1192–1199, 2016